The film features a battle between mutant human beings

X-men, which accounted for 38.6% of the total weekend takings, stars British actor Patrick Stewart - Captain Jean Luc Picard in Star Trek - as Professor Xavier, or X.

Based on the Marvel comic series that began in the 1960s, it tells the story of a battle between good and evil mutants who are mistrusted by the rest of society.

The mutants have been born with a special X-factor which gives them super-human powers and Xavier recruits a team of X-men to try and stop his old friend Erik Lehnsherr (Sir Ian McKellen) mutating the rest of society.

The film, which also stars Halle Berry, Hugh Jackman and Famke Janssen has been generally well received, but box office expert Paul Dergarabedian admitted it had done much better than anyone predicted.

Beyond expectations

"We knew this would be the number one movie," he said, "but this has performed way beyond expectations.

"Anything over $40m would have been great," he added.

Tom Sherak, the head of distribution for 20th Century Fox, which released X-men, said the presence of Shakespearean actors Stewart and McKellen had been a big factor in boosting audiences.

"They gave X-men the look of a real movie, not a comic-book movie. They added credibility," he stressed.

Last weekend's top film Scary Movie slipped to second place, but still made $26.1m (�17.4), to boost its total takings to $89m (�59.4m) in just ten days. George Clooney's The Perfect Storm was third and The Patriot, starring Mel Gibson, fourth.

Overall, the top 12 movies grossed $148.8m (�99.4m) - up 39% on the same weekend last year.

X-men is released in the UK on 18 August.